The present invention is directed to a surface sweeping machine, commonly referred to as a road sweeper, which utilizes a conventional truck body including a cab and a frame with the latter having mounted thereon a pick-up head, a hopper, a centrifugal separator, a blower, a blower housing, and associated openings and conduits for circulating air entrained debris through the centrifugal separator and thereby depositing debris in the hopper for subsequent discharge/dumping.
A typical road sweeper of the latter construction is found in U.S. Pat. Nos. 3,512,206 and 3,545,181, each in the name of Bernard W. Young granted on May 19 and Dec. 8, 1970, respectively. Debris from the hopper is discharged through a hydraulically opened and closed rear door. Over the years road sweepers have evolved and the assignee (Tymco, Inc.) of the present invention developed, manufactured, sold and patented a surface sweeping machine with over-the-cab hopper dumping, as is evidenced by U.S. Pat. No. 5,072,048 in the name of Gary B. Young et al. granted on Dec. 17, 1991. The road sweeper of this patent includes a hopper having an opening which is in registration with an opening of a blower housing during a sweeping operation but for dumping purposes the hopper can be pivoted away from the blower housing, while the blower housing and its associated blower/turbine remains stationary with respect to the vehicle frame.
A road sweeper disclosed in U.S. Pat. No. 3,634,904 granted on Jan. 18, 1972 to Gregory J. Larson (assigned to Wayne Manufacturing Company) discloses a road sweeper in which flexible and rigid conduits are connected to each other between a debris hopper and a suction hood or pick-up head. The hopper carries a rigid conduit which in turn carries an O-ring seal which mates against a plenum face of a coupling connected to a flexible conduit. The coupling is supported by both a compression spring and a link to the vehicle frame. When the hopper is returned from an open dumping position to a working position, the rigid upper conduit section carried thereby swings downwardly to engage and compress the O-ring seal against the plenum face 29 and also compresses the spring supporting the flexible conduit coupling. In accordance with the latter disclosure, the pivoting motion of the debris hopper thereby connects and disconnects the hopper conduit relative to the pick-up head.
U.S. Pat. No. 5,596,788 granted on Jan. 28, 1997 to Ronny E. Linville et al. discloses a road sweeper in which a pivotally mounted hopper has a pair of openings which align with openings of an inlet conduit leading from a pick-up head and a fan inlet flange of a vacuum fan housing. Gaskets are utilized with the latter openings to prevent air leakage and sealing surfaces or flanges associated therewith are canted to slope rearwardly and downwardly to provide complementary mating engagement between the sealing surfaces of the movable hopper and an immovable lower housing carried by the vehicle frame.